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Post by Deleted on Mar 11, 2012 5:09:04 GMT
Working on old valve amps - Sent by a friend of mine……… Well, there I was just testing a 600V 200mA power supply. I already has success with a SMPS 13V and 20A so I had good expectations. But then there was the DC out, instead of being 600V+, it was only 450V! Well I thought, “the 5AS4 rectifier must be low in emission Oh well” then the unit started to “hissss” and I turned it off quickly. But I was a bit silly, I decided to knock the capacitor off the chassis. It was one of the aluminium can type, so I hit it….. it exploded!! The noise knocked me and the chair over on to the floor. I am thankful that I was wearing my reading glasses as I got tar over them and lots of places with dirty paper EVERYWHERE!! It was quite a clean-up! Attachments:
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pagan
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Post by pagan on Mar 11, 2012 8:32:58 GMT
Alex
best thing that can happen to a valve amp ;D
Exploding cap, what a mess and It would have to absolutely stink too
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Post by Deleted on Mar 11, 2012 9:00:23 GMT
Alex best thing that can happen to a valve amp ;D Exploding cap, what a mess and It would have to absolutely stink too
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Post by billyray on Mar 11, 2012 10:28:08 GMT
Working on old valve amps from a friend of mine……… Well, there I was just testing a 600V 200mA power supply. I already has success with a SMPS 13V and 20A so I had good expectations. But then there was the DC out, instead of being 600V+, it was only 450V! Well I thought, “the 5AS4 rectifier must be low in emission Oh well” then the unit started to “hissss” and I turned it off quickly. But I was a bit silly, I decided to knock the capacitor off the chassis. It was one of the aluminium can type, so I hit it….. it exploded!! The noise knocked me and the chair over on to the floor. I am thankful that I was wearing my reading glasses as I got tar over them and lots of places with dirty paper EVERYWHERE!! It was quite a clean-up! Goodness you were lucky. Hope your friend was understanding - not that it was your fault that his kit was so iffy.
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Post by Deleted on Mar 11, 2012 10:47:33 GMT
billyray It was a friend of mine working (?) on the amp. I wouldn't have gone anywhere near that rusty old thing. Alex
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elysion
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Post by elysion on Mar 11, 2012 12:15:56 GMT
I'm glad that no one was really hurt - beside the mess and the damaged amp. The pics look quite impressive.
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rowuk
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Post by rowuk on Mar 11, 2012 20:43:04 GMT
The beauty of old valve amps is that they are mostly point to point wiring and getting it up and running again should be no major issue
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Post by Deleted on Mar 11, 2012 21:17:19 GMT
Robin I liked Allan's reply better. ;)The beauty of a rusty old valve amplifier ? Regards Alex
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XTRProf
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Post by XTRProf on Mar 13, 2012 6:23:48 GMT
Er, why will you want to knock off the cap from the chassis after having charged it up? Surely, it will explode with the charge still fresh in it. Btw, are you going to up the valve amp again? It will be good sound when working properly.
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pagan
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Post by pagan on Mar 13, 2012 7:51:21 GMT
billyray I wouldn't have gone anywhere near that rusty old thing. Alex What, the friend or the amp? ;D ;D
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Post by Deleted on Mar 14, 2012 1:56:22 GMT
The beauty of old valve amps is that they are mostly point to point wiring and getting it up and running again should be no major issue that one looks fried crisp and dry to me and I'd not trust that mains TX or choke tooo much. shame as some of those early PYE amps where pretty good. so good luck with that repair I'll sort you out one of those robotic bomb disposal thingies to work on it with. hay Alex that looks like one of my first DIY efforts mmmm i can smell the blue smoke rising even now. take care
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Post by Deleted on Mar 14, 2012 2:11:01 GMT
Hi Shaun Just to make something clear. It wasn't my amp, it was sent to me by a friend. I gave up onvalve amps >30 years ago, except for a brief re-visit to a S.C. designed preamp with a REAL H.T., supply and using NFB etc. That amp looks like something that an A.P.O. employee from Sydney's outer western suburbs may have dumped at the local tip ? ;D Regards Alex
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xerxes
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Post by xerxes on Mar 14, 2012 4:03:41 GMT
I recognise the PYE logo: en.wikipedia.org/wiki/Pye_Ltd. I'm pretty sure the black and white television we had when I was a kid was a PYE. It used valves and needed frequent repair.
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Post by Deleted on Mar 14, 2012 12:17:33 GMT
Hi Alex yes i gathered that from your first post. in a lot of ways trying to revive an old timer like the PYE can be more problematic than building from scratch. i had an old Rogers cadet11 once which ended up looking pretty much the same as your friends amp. take care
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XTRProf
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Post by XTRProf on Mar 14, 2012 15:10:18 GMT
Wah, Shaun, you practising eastern martial art? I just saw your ying yang logo at your avatar. Yup, Bruce Lee would be very proud of that as that was his school logo at one time.
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Post by Deleted on Mar 14, 2012 22:56:11 GMT
Hi Chong i was wondering when you might notice I'm practicing the art of balance in all things audio Tao baby
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Post by Deleted on Mar 14, 2012 23:08:18 GMT
Nahhhhhhhh, You're just emigrating to South Korea! yabba-say-oh, bot by-oh.
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Post by Deleted on Mar 14, 2012 23:24:41 GMT
Nahhhhhhhh, You're just emigrating to South Korea! yabba-say-oh, bot by-oh. who is that masked man?
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XTRProf
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Post by XTRProf on Mar 15, 2012 4:50:05 GMT
Peace at last!
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Post by Deleted on Mar 15, 2012 10:15:25 GMT
Peace at last! Hi Chong now how do we say that in Hokien? take care
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XTRProf
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Post by XTRProf on Mar 15, 2012 10:53:59 GMT
Peace at last! Hi Chong now how do we say that in Hokien? take care I love you - Wa ai lu
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Deleted
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Post by Deleted on Mar 15, 2012 10:59:15 GMT
kong ka wa tao tia
have you any asprin Chong
Tao Baby
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XTRProf
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Post by XTRProf on Mar 15, 2012 11:11:35 GMT
have you any asprin Chong Ha, ha, my secondary school Malay chegu used to tell us to have a Panadol (meaning a hit on the head each with a book) when we were naughty! Yeah, we always greeted him chiku when he came to start a class in the Malay language. Check out chiku!
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Post by Deleted on Mar 15, 2012 20:34:58 GMT
Hi Chong
and plums to you too ;D ;D ;D
take care
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